What is the meaning of the medical abbrevaition i & o?

Input & Output: At least in hospital setting, especially for patients who come in w. Dehydration or possibly heart issues, nurses are requested by doctors to keep track of the amount of fluids going in - both orally and by intravenously, and the amount that comes out of our patients by urine, feces +-diarrhea, and vomitting to be able to make sure of good or desired fluid balance.

Dr Villaplana agreed

Ins and Outs: This is typically used in a hospital setting and describes measuring the intake and output a patient has over a 24 hour period. All the food and liquids are the ins and urine and bms are the outs. Usually, however, only the liquids are measured to determine the patients fluid balance and whether they are able to put out whatever is taken in.

Dr Villaplana and another doctor agreed

Intake & output: Doctors often request accurate records of a patient's intake & output to prevent dehydration, monitor kidney function, prevent fluid overload, monitor caloric intake, etc.

Dr Schomberg-Klaiss agreed